To advance miniaturization and integration of electronic devices to be mounted on electronic equipment such as mobile telephones, the MEMS (Micro Electro Mechanical Systems) technology is going to be adopted. The electronic devices manufactured by the MEMS technology include, for example, switch elements and variable capacitors.
In these electronic devices, a metal thin film is attracted with electrostatic force or the like, so that the metal thin film is caused to have a function as a movable portion. For example, in a switch element, a metal thin film is used as a cantilever. The cantilever to be bent with electrostatic force is brought into contact with a terminal to perform switching. In addition, in a variable capacitor, a metal thin film is used as a movable electrode for a capacitor and a distance between electrodes is caused to be variable with application of electrostatic force.
A bending amount of the movable portion may be controlled by a magnitude of the electrostatic force to be applied. Then, in the electronic device including such a movable portion, it is preferable that even when the ambient temperature is changed, the magnitude of the electrostatic force to be applied do not change and the same electric characteristics be always obtained.    Patent document 1: Japanese Laid-open Patent Publication No. 05-190617    Patent document 2: Japanese Laid-open Patent Publication No. 2006-55991    Patent document 3: Japanese Laid-open Patent Publication No. 01-179286